Field of the Invention:
The invention relates to a method for modeling and executing a production rule in a discrete manufacturing scenario, especially in the field of manufacturing execution systems.
Discrete manufacturing is related to production or assembly of discrete parts easily identifiable. Main characteristics of this category of manufacturing are low level automation or relevant manual activities, high flexibility and uncertainty of information. Depending on the scenario, there may be few processes running concurrently. In many cases the processes don't run continuously, but they are rather composed of a number of single steps which have to be carried out at certain points in time, mostly according to a manual schedule, meaning that an operator triggers each step manually, rather than a schedule provided by a process controller. In these scenarios, a continuously active process doesn't fit very well in a production phase, as only short actions have to be carried out and long pauses follow.
Prior art solutions, in automatizing a production phase, use an approach of modeling a production process by specifying a single production rule coordinated by the process controller. Usual situations in the discrete manufacturing scenario, like for example pause, manual command, start of a small portion of the production rule, etc., is managed by waiting for events, thus setting the production rule in an infinite loop state until a certain event occurs, in other words pausing the production rule, but always leaving the production rule active. Consequently, resources of the process controller are consumed by keeping the rule active but paused. Furthermore, the process controller has to distinguish between numerous events received and dispatch the correct event to the production rule, thus causing a high CPU effort.